Effect of mesozoic sandstone meso structure on strength and energy dissipation characteristic

The mesozoic medium particle sandstone slices of northeastern and western coal mines were observed under microscope,and the mineral particles,cementing composition and crystallization degree were analyzed for the following triaxial cell loading and cyclic loading acoustic emission ( AE) experiments. The variation laws of strength criterion, dissipated energy,Kaiser effect and load / unload response ratio ( LURR) were discussed. The results show that the northeastern calcareous cemented sandstones show a higher strength than that of the western calcareous argillaceous cemented specimens by the Mohr-Coulomb criterion. At the equal stress level the northeastern sandstone elastic energy is higher and the dissipated energy is lower comparing with western sandstone. During the cyclic loading,the Kaiser effect usually occurs at the elastic stage within low stress level,and the northeastern specimens contains more Kaiser points than that of western specimens. As the stress increases,the LURR decreases sharply at low stress stage,then de- clines steadily,and reaches minimum at the peak strength,moreover the northeastern sandstone LURR is lower than that of the western specimens. The differences of the mechanics and energy dissipation can be ascribed to the diversity of cementing composition and crystallization lithogenesis degree.